nf: fix potential bug in nfnl_queue_msg_set_payload() when malloc() failed
nf: fix potential bug in nfnl_queue_msg_set_payload() when malloc() failed

Suppose the case:
1. message have already some payload
2. malloc() failed

In that case:
1. msg->queue_msg_payload become NULL
2. msg->queue_msg_payload_len stay non-zero

Now when malloc() error occurs, nothing changed.

https://github.com/thom311/libnl/pull/83

tklauser/libnl,thom311/libnl,HolyShitMan/libnl-1,HolyShitMan/libnl-1,greearb/libnl-ct,HolyShitMan/libnl-1,dsahern/libnl,mshirley/libnl,kolyshkin/libnl,dsahern/libnl,tklauser/libnl,tklauser/libnl,kolyshkin/libnl,mshirley/libnl,dsahern/libnl,HolyShitMan/libnl-1,greearb/libnl-ct,thom311/libnl,mshirley/libnl,kolyshkin/libnl,greearb/libnl-ct,mshirley/libnl,kolyshkin/libnl,thom311/libnl,dsahern/libnl,tklauser/libnl